The drawbacks of climate change are so overt. The Disturbance of Great Ocean Conveyor currents led to the extreme changes in temperature around the globe in the form of a cooler northern, warmer tropical and cooler snowy winter, warmer summer. Many deaths from hypothermia were reported especially in refugee camps as it is not well equipped. Hypothermia is a medical emergency that occurs when the body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia occurs as the body temperature falls below 95 F (35 C). When body temperature drops, heart, nervous system and other organs can't work normally. Left untreated, hypothermia can eventually lead to complete failure of heart and respiratory system and eventually to death.

1. HYPOTHERMIA
Dr. Fathi Neana, MD
Chief of Orthopaedics
Dr. Fakhry & Dr. A. Al-Garzaie Hospital
February, 5 - 2020

3. Climate change
Global warming
Greenhouse phenomenon
El Niño
Heavy rains & flooding in new sites (Cities)
Desertification of original sites (Africa ..)
Tropical cyclones
Methane clathrate emission
Earthquakes
Volcano eruptions
Global Dimming
Agricultural effect

4. 1- THE Industrial Revolution
Began in Great Britain. Begin meaningfully in the
late 19th and 20th centuries. Over the past 150
years
We’ve changed the balance of our planet by living
beyond our means
2- Fossil fuels
We’ve burnt huge amounts of fossil fuels (such as
coal, oil, gas) – CO2
We’ve bred huge amounts of methane- producing
livestock
Climate Change

5. 3- Deforestation
We’ve cut down vast swathes of forests,
which would naturally absorb carbon
dioxide from the air
(Deforestation, clearance or clearing of
forests)
4- Greenhouse gases (GHG)
accumulation of:
Water vapor
Carbon dioxide
Methane
Nitrous oxide
Ozone
Climate Change

7. ‫الدخان‬ ‫سورة‬-‫سورة‬44
َ‫ون‬ُ‫ب‬َ‫ع‬ْ‫ل‬َ‫ي‬ ٍّ‫َك‬‫ش‬ ‫ي‬ِ‫ف‬ ْ‫م‬ُ‫ه‬ ْ‫ل‬َ‫ب‬(9)ٍّ‫ين‬ِ‫ب‬ُّ‫م‬ ٍّ‫ان‬َ‫خ‬ُ‫د‬ِ‫ب‬ ُ‫ء‬‫ا‬َ‫م‬َّ‫س‬‫ال‬ ‫ي‬ِ‫ت‬ْ‫أ‬َ‫ت‬ َ‫م‬ ْ‫و‬َ‫ي‬ ْ‫ب‬ِ‫ق‬َ‫ت‬ْ‫ار‬َ‫ف‬(10)ٌ‫م‬‫ي‬ِ‫ل‬َ‫أ‬ ٌ‫اب‬َ‫ذ‬َ‫ع‬ ‫ا‬َ‫ذ‬ََٰ‫ه‬ ۖ َ‫اس‬َّ‫ن‬‫ال‬ ‫َى‬‫ش‬ْ‫غ‬َ‫ي‬(11)
Then watch thou for the Day that the sky will bring forth a kind of smoke (or mist)
plainly visible (10). Ad-Dukhaan (44)

8. 5- Global warming
6- Melting of ice in the poles
7- Disturbance of Great Ocean
Conveyor currents
Cooler northern – Warmer tropical
Cooler winter (snow) – Warmer summer
8- El Niño
Climate Change

9. The great ocean conveyor moves water around
the globe. ... There is constant motion in
the ocean in the form of a global ocean
conveyor belt. This motion is caused by a
combination of
1- Thermohaline currents (thermo =
temperature; haline = salinity) in the
deep ocean and
2- Wind-driven currents on the surface.
Disturbance of Great Ocean Conveyor currents
Cooler northern – Warmer tropical - Cooler winter (snow) – Warmer summer

11. With Cold Temp’s Remember the 4 P’s: People,
Pets, Plants, and Pipes
January 18, 2019 by Julie Lawrence
In anticipation of the cold air mass moving in to our
area Sunday bringing colder temperatures and wind
chills in the teens, Elmore County EMA would like to
remind our citizens of the 4 P’s: People, Pets,
Plants, and Pipes.
People – should dress warmly, in layers, to avoid
hypothermia (abnormally low body temperature).
Pets – should be brought indoors or provided with a
warm place to sleep.
Pipes – that run outside or under a house should be
wrapped in pipe insulation to avoid cracks due to
water freezing in them.
Plants – may need to be covered or brought inside
to avoid frost damage.

13. A core body temperature below
96.8oF (< 35 C)
Mild hypothermia = 92 – 96.8oF (32-35 C)
Moderate = 88 – 92oF (32-27 C)
Severe = < 88oF (<27 C)
“They’re not dead until they’re warm and
dead.”
One case report of recovery after accidental
15.2oC (59.4F) hypothermia.
What is hypothermia?

14. Hypothermia is a medical emergency
that occurs when your body loses heat faster than it can
produce heat, causing a dangerously low body
temperature.
Normal body temperature is around 98.6 F (37 C).
Hypothermia (hi-poe-THUR-me-uh) occurs as your body
temperature falls below 95 F (35 C).
When body temperature drops, heart, nervous system and
other organs can't work normally.
Left untreated, hypothermia can eventually lead to
complete failure of heart and respiratory system and
eventually to death.
What is hypothermia?
Hypothermia is often caused by exposure to cold weather or immersion in cold
water. Primary treatments for hypothermia are methods to warm the body back to a
normal temperature.

15. Hypothermia is a core body
temperature < 35° C.
Symptoms progress from shivering and
lethargy to confusion, coma, and death.
Mild hypothermia requires a warm
environment and insulating blankets
(passive rewarming).
Severe hypothermia requires active
rewarming of the body surface (eg, with
forced-air warming systems, radiant
sources) and core (eg, inhalation, heated
infusion and lavage, extracorporeal blood
rewarming).
Primary hypothermia causes about 600 deaths each year in the US.
Hypothermia also has a significant and under recognized effect on mortality
risk in cardiovascular and neurologic disorders
, MD, University of Louisville School of Medicine
Content last modified May 2019
What is hypothermia?

16. The hypothalamus is the
temperature control center
Core and peripheral receptors
provide temperature information
Various responses help maintain
temperature homeostasis
Cut heat loss; generate heat!
Physiology

18. Basal heat production (40-60kcal/m2 of Body Surface
Area)
• Increased with food, muscle activity, fever and acute
cold
Exposure
• Max production lasts for a few hrs (Because of fatigue
and glycogen depletion)
Movement, shivering can increase the BMR 2 to 5 x
normal
Physiology
Heat Generation

19. 4 ways heat is lost
• Radiation (65%) most important by electromagnetic waves
• Evaporation (25%): liquid to a gas 0.56 kcal/ml of evaporated
H2O
• Convection (10-15%) heat loss to air and vapor circulating
around the body wind temp and velocity
• Conduction (2+ %): direct contact (important with immersion
; cold water conductivity 32 times that of air)
Physiology
The physics of temperature
homeostasis

21. Our body responds to decreased
temperature by attempting to:
Decrease heat loss
Vasoconstriction
Behavior modification
Increase heat production
Shivering
Am J Physiol 1997 Feb
• 37-32 C : vasoconstriction, shivering , non shivering endocrine thermogenesis
• 32-24 C : progressive reduction in basal metabolic rate (NO shivering)
• <24 C : autonomic and endocrine mechanisms inactive
Physiology
Our body responds to decreased temperature

22. Etiology Overview
Increase in heat loss
Decrease in heat production
Thermoregulatory failure
Etiology of hypothermia

23. Etiology of hypothermia
Increased Heat Loss
Hypothermia results when body heat loss
exceeds body heat production.
Hypothermia is most common during
1- Cold weather
2- Immersion in cold water,
3- May occur in warm climates
when people lie immobile on a cool surface
(eg, when they are intoxicated) or after very
prolonged immersion in swimming-
temperature water (eg, 20 to 24°C).
Wet clothing and wind increase risk of
hypothermia.
Significant risk begins in water colder than 25
C (72 F). The water temperature of Lake Huron
is approximately 4.6 C (40 F) in May and is
highest in August at 19 C (66 F).
- Hypothermia can occur rapidly during cold-
water immersion (one hour or less when water
temperature is below 45oF).
-Core temp drops 0.3C in 20 min when
immersed in 22C
(Am J Phys Med Rehabil 1999 Jan-Feb;
78(1):33-8.

24. Exposure to ambient temperature drop
Sports
Altitude
Immersion
Conditions that cause loss of
consciousness, immobility, or both are
common predisposing factors
Trauma
Hypoglycemia
Seizure disorders
Stroke
Drug or alcohol intoxication)
Etiology of hypothermia
Increased Heat Loss

25. Acute Illness
Metabolic abnormalities
Diabetic KA
Hypoglycemia
Myxedema coma
Hypoadrenalism
Etiology of hypothermia
Decreased Heat Production

26. Sepsis
V lymphocyte activation
V IL-1,2,6 (Anesthesiology 1998
Nov; 89(5):1133-40. J Neurotrauma 1999 Mar; 16(3): 225-32)
CVA
Autonomic dysfunction
Etiology of hypothermia
Impaired Thermoregulation

27. •Exhaustion. Your tolerance for cold diminishes when you are fatigued.
•Older age. The body's ability to regulate temperature and to sense cold may lessen with age. And some
older adults may not be able to communicate when they are cold or to move to a warm location if they do feel
cold.
•Very young age. Children lose heat faster than adults do. Children may also ignore the cold because
they're having too much fun to think about it. And they may not have the judgment to dress properly in cold
weather or to get out of the cold when they should.
•Mental problems. People with a mental illness, dementia or other conditions that interfere with judgment
may not dress appropriately for the weather or understand the risk of cold weather. People with dementia may
wander from home or get lost easily, making them more likely to be stranded outside in cold or wet weather.
•Alcohol and drug use. Alcohol may make your body feel warm inside, but it causes your blood vessels to
expand, resulting in more rapid heat loss from the surface of your skin. The body's natural shivering response is
diminished in people who've been drinking alcohol. In addition, the use of alcohol or recreational drugs can
affect your judgment about the need to get inside or wear warm clothes in cold weather conditions. If a person
is intoxicated and passes out in cold weather, he or she is likely to develop hypothermia.
•Certain medical conditions. Some health disorders affect your body's ability to regulate body
temperature. Examples include an underactive thyroid (hypothyroidism), poor nutrition or anorexia nervosa,
diabetes, stroke, severe arthritis, Parkinson's disease, trauma, and spinal cord injuries.
•Medications. Some drugs can change the body's ability to regulate its temperature. Examples include
certain antidepressants, antipsychotics, narcotic pain medications and sedatives.
Risk factors for hypothermia

28. The elderly:
•often have diminished temperature sensation
•impaired mobility and communication Poor adaptive and behavioral responses
•diminished subcutaneous fat
• Dec muscle mass and glycogen stores for shivering
• Poor glucose use
• Autonomic dysfunction- poor vasoconstrictive ability
• Co morbid illness, Peripheral vascular disease, CNS dysfunction, Cardiac disease
The very young:
•diminished mobility and communication
•increased surface area/mass ratio, which enhances heat loss.
Alcohol (ethanol) use with hypothermia (false):
1. Interacts with every neurotransmitter in brain
2. Metabolized faster in hypothermic patients
3. Possible direct damage to hypothalamus
4. Cutaneous vasodilation, impaired shivering
5. Impaired cognition and immobility, Decreased awareness of environment
6. Hypoglycemia and/or malnutrition
7. Wernicke’s encephalopathy
Eur J Appl Physiol 1996;74(3):293-5. Also, Ann Neurol 1981 Oct; 10(4):384-7)
Risk factors for hypothermia

29. Hypothermia slows all physiologic functions, including cardiovascular and respiratory systems,
nerve conduction, mental acuity, neuromuscular reaction time, and metabolic rate.
Thermoregulation ceases below about 30° C; the body must then depend on an external heat source
for rewarming.
Renal cell dysfunction and decreased levels of vasopressin (ADH) lead to production of a large
volume of dilute urine (cold diuresis). Diuresis plus fluid leakage into the interstitial tissues causes
hypovolemia.
Vasoconstriction, which occurs with hypothermia, may mask hypovolemia, which then manifests as
sudden shock or cardiac arrest during rewarming (rewarming collapse) when peripheral vasculature
dilates.
Immersion in cold water can trigger the diving reflex, which involves reflex vasoconstriction in
visceral muscles; blood is shunted to essential organs (eg, heart, brain).
The reflex is most pronounced in small children and may help protect them.
Also, hypothermia due to total immersion in near-freezing water may protect the brain from hypoxia
by decreasing metabolic demands.
The decreased demand probably accounts for the occasional survival after prolonged cardiac arrest
due to extreme hypothermia.
Impact on Organ Systems
Pathophysiology

30. Respiratory
Altitude will decrease Po2
Temperature of inspired air
decreased
• Air warmed + humidified by oral/nasal mucosa prior
to hitting lower airways
• Expired air rich in warm water – heat lost
Initial ↑in RR then ↓ RR proportional to ↓
metabolism
CO2 retention & RS acidosis in sev. hypothermia.
Bronchorrhea, ↓ciliary motility and noncardiogenic
pulm edema
Impact on Organ Systems

31. Hemoglobin increasingly binds O2 as temperature drops (oxyhemoglobin
dissociation curve)
Hypoxia may occur due to decrease offloading of oxygen
(Cardiovasc Surg 1999 Jun;7(4):425-31
Impact on Organ Systems

32. Acid-base balance
11/18 with decompensated metabolic
acidosis
(Coll Antropol 1999 Dec;23(2):683-90
Most texts recommend not correcting
for temperature when evaluating ABGs
Impact on Organ Systems
Cardiac
Repolarization becomes abnormal
with decreasing temperature
Osborn Wave – lead V3 or V4
Increasing cardiac irritability with
decreasing temperature
QT prolongation (0.45-0.688 vs.
0.343-0.444; Coll Antropol 1999
Dec; 23(2):683-90)
Osborn Wave
86% of hypothermic patients (Acad
Emerg Med 1999 Nov; 6(11):1121-6)
Voltage gradient due to action
potential notch in epicardium;
epicardium activated later, which
manifests as notching or J-point
elevation (Circulation 1996 Jan
15;93(2):372-9)

34. Cardiac
Mild: Tachycardia, hypertension, increased CO
Moderate: Bradycardia, Arrhythmias
Severe: Arrhythmias, hypotension, decreased cardiac
output
Below 30C, ventricular fibrillation risk increases
Impact on Organ Systems

35. Neurologic
Decreasing metabolic activity of neurons; therefore, decreased O2
Requirement
Linear decrease in CNS function as temperature decreases
Neuron function stops below 20C
Decline in mental status
Mild confusion
Delirium
Coma
Peripheral anesthesia
Ataxia
Impact on Organ Systems

36. Renal
Hypothermia impairs renal concentrating abilities
“Cold-induced diuresis”
Potential rhabdomyolysis -> ATN
Gastrointestinal
Pancreatitis ± pancreatic necrosis
can develop due to HT
Hematologic
Hemoconcentration
Increased blood viscosity
Decreased flow in capillaries
Potential for thrombosis
Potential for DIC
Impact on Organ Systems

37. Musculoskeletal
Temperature extremes can cause
crystallization of blood in capillaries of
extremities
Cutaneous vasoconstriction occurs in
response to lower ambient Temperature
Frostbite
Gangrene
Impact on Organ
Systems

38. Musculoskeletal
Frostbite
Grade as burns
1st degree
- Erythema, edema, burning
- Swelling for ten days or more
-Desquamation
- Parathesias, aching, and necrosis
of the pressure points of the foot
-Increased sensitivity to cold,
Hyperhydrosis
Second degree
- progresses to blister formation,
anesthesia, and deep color change
Impact on Organ Systems
Third degree
- involves full skin thickness and
extends into the subcutaneous
tissue
- Subfascial pressure increases;
compartment syndromes are
Common
4th degree
- Destruction of entire thickness
- Cyanotic, insensitive; hemorrhagic
blister formation.
- Severe pain on rewarming
- Dry gangrene can progress quickly
with mummification.
- The line of demarcation becomes
obvious at 20-36 days and extends
into the bone in 60 or more days.

39. Impact on Organ Systems
Musculoskeletal
Trench foot
Caused by prolonged exposure of the feet to cool, wet
conditions.
The skin is initially reddened with numbness, tingling pain,
and itching then becomes pale and mottled and finally dark
purple, grey or blue.
If circulation is impaired for more than 6 hours there will
be permanent damage to tissue.
If circulation is impaired for more than 24 hours the victim
may lose the entire foot.

40. Clinical features
Shivering is likely the first thing you'll notice as the temperature starts to drop
because it's your body's automatic defense against cold temperature — an attempt
to warm itself.
Signs and symptoms of hypothermia include:
•Shivering
•Slurred speech or mumbling
•Slow, shallow breathing
•Weak pulse
•Clumsiness or lack of coordination
•Drowsiness or very low energy
•Confusion or memory loss
•Loss of consciousness
•Bright red, cold skin (in infants)
Someone with hypothermia usually isn't aware of his or her condition because the
symptoms often begin gradually. Also, the confused thinking associated with
hypothermia prevents self-awareness. The confused thinking can also lead to risk-
taking behavior.

41. Mild: shivering, loss of fine motor control
Moderate: lethargy, confusion
Severe: pupillary dilation, coma, cardiovascular irritability and eventual
collapse
Clinical features
Intense shivering occurs initially, but it ceases below about 31° C, allowing body temperature
to drop more precipitously.
Central nervous system dysfunction progresses as body temperature decreases; people do
not sense the cold.
Lethargy and clumsiness are followed by confusion, irritability, sometimes hallucinations, and
eventually coma.
Pupils may become unreactive.
Respirations and heartbeat slow and ultimately cease.
Initially, sinus bradycardia is followed by slow atrial fibrillation; the terminal rhythm is ventricular
fibrillation or asystole.

42. Head-to-toe secondary exam
Neuro exam important – especially cranial
nerves (Wernicke’s)
CV exam
Extremities/nose/ears/other endarterial
Places
Testing
Cardiac monitor, EKG
SaO2, ±ABG
Electrolytes, CBC
UA
If severe:
LFTS, PT/PTT, CK (rhabdo)
Hypothermia
Identification & Evaluation
Thermometry
- Most thermometers’ lower temperature
limit is 93oF(33.8889 Celsius)
- A special low-temperature-reading
thermometer is necessary to read
temperatures lower than 93
ABCDEs are the priority
Handle patients gently
Begin passive rewarming immediately
Cautious ACLS care (coming up)
History is essential
Environment/exposure
PMH
Medications
Exam – be complete!
Rectal temperature!
Vital signs

43. Hypothermia
Identification & Evaluation
•Core temperature measurement
•Consideration of intoxication, myxedema, sepsis, hypoglycemia, and trauma
Diagnosis is by core temperature, not oral temperature. Electronic thermometers are
preferred; many standard mercury thermometers have a lower limit of 34° C. Rectal and
esophageal probes are most accurate.
Laboratory tests include complete blood count, glucose (including bedside measurement),
electrolytes, blood urea nitrogen, creatinine, and arterial blood gases (ABGs). ABGs are not
corrected for low temperature.
An electroencephalogram (EEG) may show J (Osborn) waves (see figure Abnormal ECG
showing J [Osborn] waves [V4]) and interval prolongation (PR, QRS, QT). If the cause of
hypothermia is unclear, tests to detect contributing factors are done, including measuring the
alcohol level and screening for drugs and thyroid function. Sepsis and occult head or skeletal
trauma must be considered.
Abnormal ECG showing J (Osborn) waves (V4)

44. Mild hypothermia – very little
Moderate – one study showed a mortality rate of 21% for moderate hypothermia
Hypothermia
Morbidity/Mortality
Prognosis
Patients who have been immersed in icy water for 1 hour or (rarely) longer have sometimes
been successfully rewarmed without permanent brain damage (see Drowning: Prognosis),
even when core temperatures were very low or when pupils were unreactive. Outcome is
difficult to predict and cannot be based on the Glasgow Coma Scale.
Grave prognostic markers include:
•Evidence of cell lysis (serum potassium > 10 mEq/L [10 mmol/L])
•Intravascular thrombosis (fibrinogen < 50 mg/dL [1.47 micromol/L])
•A nonperfusing cardiac rhythm (ventricular fibrillation or asystole)
For a given degree and duration of hypothermia, children are more likely to recover than
adults.

45. Treatment
•Drying and insulation
•Fluid resuscitation
•Passive rewarming In mild hypothermia (temperature 32.2 to 35° C) with intact
thermoregulation
•Active rewarming unless hypothermia is mild, accidental, and uncomplicated
•The first priority is to prevent further heat loss by removing wet clothing and
insulating the patient.
•Subsequent measures depend on how severe hypothermia is and whether
cardiovascular instability or cardiac arrest is present.
•Returning patients to a normal temperature is less urgent in hypothermia than in
severe hyperthermia.
•For stable patients, elevation of core temperature by 1° C/hour is acceptable.
•Fluid resuscitation is essential for hypovolemia. Patients are given 1 to 2 L of 0.9%
saline solution (20 mL/kg for children) IV; if possible, the solution is heated to 40 to
42° C. More fluid is given as needed to maintain perfusion.

46. 1- General Rx for various
degrees of Hypothermia
2- Specific Rx for sequelae
- CV
- Respiratory
- ATN/Rhabdomyolysis
- Frostbite/gangrene
Treatment

47. Mild hypothermia
Passive rewarming
(temperature 32.2 to 35° C) with intact
thermoregulation (indicated by shivering)
Insulation in Warm room
Cover with dry, warm blankets
Warm fluids to drink
Radiant warming
Treatment
General Rx for various degrees of Hypothermia

48. Moderate hypothermia
Active rewarming
ABCs – every patient
- Airway, Breathing – warm,
humidified air by ETT or NRBfm
- Circulation – IV access; warmed
crystalloid
All of the above
Bear Hugger
Treatment
General Rx for various degrees of Hypothermia

50. Severe Hypothermia
Active rewarming
All of the above
Invasive modalities
- NG, foley lavage
- Pleural, peritoneal lavage
- Dialysis or Cardiac bypass
Treatment
General Rx for various degrees of Hypothermia

51. Active rewarming is required if patients have temperature < 32.2° C,
cardiovascular instability, hormone insufficiency (such as hypoadrenalism or
hypothyroidism), or hypothermia secondary to trauma, toxins, or predisposing
disorders.
In moderate hypothermia, body temperature is at the warmer end of the range
(28 to 32.2° C), and external rewarming with forced hot air enclosures may be
used. External heat is best applied to the thorax because warming the extremities
may increase metabolic demands on a depressed cardiovascular system.
Active rewarming

52. In severe hypothermia, patients with lower temperatures (< 28° C), particularly
those with low blood pressure or cardiac arrest, require core rewarming. Core
rewarming options include
•Inhalation
•IV infusion
•Lavage
•Extracorporeal core rewarming (ECR)
Inhalation of heated (40 to 45° C), humidified oxygen via mask or endotracheal tube eliminates
respiratory heat loss and can add 1 to 2° C/hour to the rewarming rate.
IV crystalloids or blood should be heated to 40 to 42° C, especially with massive volume resuscitations.
Closed thoracic lavage through 2 thoracostomy tubes(see How to Do Tube Thoracostomy) is very
efficient in severe cases. Peritoneal lavage with dialysate heated to 40 to 45° C requires 2 catheters with
outflow suction and is especially useful for severely hypothermic patients who have rhabdomyolysis, toxin
ingestions, or electrolyte abnormalities. Heated lavage of the bladder or gastrointestinal tract transfers
minimal heat.
There are 5 types of ECR: hemodialysis, venovenous, continuous arteriovenous, cardiopulmonary
bypass, and extracorporeal membrane oxygenation. ECR measures require a prearranged protocol with
appropriate specialists. Although they are intuitively attractive and heroic, these measures are not
routinely available, and they are not commonly used in most hospitals.
Active rewarming

53. Ventricular Fibrillation; MI
Renal Failure
DIC
Frostbite
Gangrene
Afterdrop
- Paradoxical drop in core temp
during rewarming
- Due to influx of cold blood from
periphery
- Can precipitate arrhythmias
Treatment
Specific Rx for sequelae

54. Ventricular fibrillation
Cold heart very irritable
Will not respond to multiple rounds
of drugs
Shock – 3 times, then wait until
warm
Bretylium your drug of choice
(ACLS Guidelines)
Treatment
Specific Rx for sequelae

55. Cardiopulmonary resuscitation (CPR)
Hypotension and bradycardia are expected when core temperature is low and, if due solely to
hypothermia, need not be aggressively treated.
When needed, endotracheal intubation after oxygenation must be done gently to avoid
precipitating a nonperfusing rhythm.
CPR should be withheld if patients have a perfusing rhythm unless true cardiac arrest is
confirmed by absence of cardiac motion on bedside cardiac ultrasonography. Treat with fluids
and active rewarming. Chest compressions are not done, because
•Pulses may quickly return with rewarming
•Chest compressions may convert the perfusing rhythm to a nonperfusing one
Patients with a nonperfusing rhythm (ventricular fibrillation or asystole) requireCPR. Chest
compressions and endotracheal intubation are done. Defibrillation is difficult if body
temperature is low; one attempt with a 2 watt sec/kg charge may be made, but if ineffective,
further attempts are generally deferred until temperature reaches > 30° C.
Advanced life support should be continued until temperature reaches 32° C unless obviously
lethal injuries or disorders are present. However, advanced cardiac life-support drugs (eg,
antiarrhythmics, vasopressors, inotropes) are usually not given. Low-dose dopamine (1 to 5
mcg/kg/min) or other catecholamine infusions are typically reserved for patients who have
disproportionately severe hypotension and who do not respond to fluid resuscitation and
rewarming. Severe hyperkalemia (> 10 mEq/L [10 mmol/L]) during resuscitation typically
indicates a fatal outcome and can guide resuscitation efforts.

56. Renal Failure
Rhabdomyolysis : force fluids;
alkalinization
Cold-diuresis : fluids, watch
electrolytes
Treatment
Specific Rx for sequelae

57. Frostbite
Narcotics!
Warm water immersion – warm,
wet heat is best.
Do NOT warm then allow to
refreeze. Better to keep frozen
until definitive care is available.
Treatment
Specific Rx for sequelae

58. Afterdrop
Try to avoid – aggressive rewarming
Expect arrhythmias, be prepared to
treat
Treatment
Specific Rx for sequelae
Pearls & Pitfalls
 With moderate to severe hypothermia, core temperature must be
stabilized before rewarming the extremities,
 to prevent sudden cardiovascular collapse (rewarming collapse) when
peripheral vasculature dilates.

59. Staying warm in cold weather
Before you or your children step out into cold air, remember the advice that follows with the
simple acronym COLD — cover, overexertion, layers, dry:
•Cover. Wear a hat or other protective covering to prevent body heat from escaping from your
head, face and neck. Cover your hands with mittens instead of gloves.
•Overexertion. Avoid activities that would cause you to sweat a lot. The combination of wet
clothing and cold weather can cause you to lose body heat more quickly.
•Layers. Wear loosefitting, layered, lightweight clothing. Outer clothing made of tightly woven,
water-repellent material is best for wind protection. Wool, silk or polypropylene inner layers hold
body heat better than cotton does.
•Dry. Stay as dry as possible. Get out of wet clothing as soon as possible. Be especially careful
to keep your hands and feet dry, as it's easy for snow to get into mittens and boots.
Keeping children safe from the cold
To help prevent hypothermia when children are outside in the winter:
•Dress infants and young children in one more layer than an adult would wear in the same
conditions.
•Bring children indoors if they start shivering — that's the first sign that hypothermia is starting.
•Have children come inside frequently to warm themselves when they're playing outside.
•Don't let babies sleep in a cold room.
Prevention

60. Winter car safety
Whenever you're traveling during bad weather, be sure someone knows where you're headed
and at what time you're expected to arrive. That way, if you get into trouble on your way,
emergency responders will know where to look for your car.
It's also a good idea to keep emergency supplies in your car in case you get stranded. Supplies
may include several blankets, matches, candles, a clean can where you can melt snow into
drinking water, a first-aid kit, dry or canned food, a can opener, tow rope, booster cables,
compass, and a bag of sand or kitty litter to spread for traction if you're stuck in the snow. If
possible, travel with a cellphone.
If you're stranded, put everything you need in the car with you, huddle together and stay
covered. Run the car for 10 minutes each hour to warm it up. Make sure a window is slightly
open and the exhaust pipe isn't covered with snow while the engine is running.
Alcohol
To avoid alcohol-related risks of hypothermia, don't drink alcohol:
•If you're going to be outside in cold weather
•If you're boating
•Before going to bed on cold nights
Prevention

61. Cold-water safety
Water doesn't have to be extremely cold to cause hypothermia. Any water that's colder than normal body
temperature causes heat loss. (8, p2) The following tips may increase your survival time in cold water if you
accidentally fall in:
•Wear a life jacket. If you plan to ride in a watercraft, wear a life jacket. A life jacket can help you stay alive
longer in cold water by enabling you to float without using energy and by providing some insulation. Keep a
whistle attached to your life jacket to signal for help.
•Get out of the water if possible. Get out of the water as much as possible, such as climbing onto a capsized
boat or grabbing onto a floating object.
•Don't attempt to swim unless you're close to safety. Unless a boat, another person or a life jacket is close
by, stay put. Swimming will use up energy and may shorten survival time.
•Position your body to minimize heat loss. Use a body position known as the heat escape lessening
position (HELP) to reduce heat loss while you wait for assistance. Hold your knees to your chest to protect the
trunk of your body. If you're wearing a life jacket that turns your face down in this position, bring your legs
tightly together, your arms to your sides and your head back.
•Huddle with others. If you've fallen into cold water with other people, keep warm by facing each other in a
tight circle.
•Don't remove your clothing. While you're in the water, don't remove clothing because it helps to insulate you
from the water. Buckle, button and zip up your clothes. Cover your head if possible. Remove clothing only after
you're safely out of the water and can take measures to get dry and warm.
Prevention

62. Help for at-risk people
For people most at risk of hypothermia — infants, older adults, people who have mental or
physical problems, and people who are homeless — community outreach programs and social
support services can be of great help. If you're at risk or know someone at risk, contact your
local public health office for available services, such as the following:
•Assistance for paying heating bills
•Check-in services to see if you and your home are warm enough during cold weather
•Homeless shelters
•Community warming centers, safe and warm daytime locations where you can go
during cold weather
Prevention

63. Physiology plays a HUGE role
Etiology
Treatment
History is key
Rectal temp with low-reading thermometer
Treat temperature aggressively, but handle patient gently
Watch for afterdrop!
Key Points

64. •Measure core temperature in the rectum or esophagus using an electronic
thermometer or probe.
•Above about 32° C, passive rewarming, heated or forced-air blankets and
warm drinks are adequate treatment.
•Below about 32° C, active rewarming should be done, typically using
forced-air hot air enclosures; heated, humidified oxygen; warm IV fluid; and
sometimes heated lavage or extracorporeal methods (eg, cardiopulmonary
bypass, hemodialysis).
•At lower temperatures, patients are hypovolemic and require fluid
resuscitation.
•CPR is not done if there is a perfusing rhythm.
•When CPR is done in patients with a nonperfusing rhythm, defibrillation is
deferred (after one initial attempt) until temperature reaches about 30° C.
•Advanced cardiac life-support drugs are usually not given.
Key Points

65. References
Hypothermia
By Daniel F. Danzl, MD, University of Louisville School of Medicine
Last full review/revision May 2019| Content last modified May 2019
Hypothermia
David Caro, MD University of Florida Emergency Medicine (slide share)
Ann Emerg Med 1993 Feb;22(2 Pt 2):370-7
Wilderness Medicine – Auerbach
Rosen’s Principles of Emergency Medicine
Hypothermia
Noora Al-Sukaiti R2 (slide share)
Hypothermia - Symptoms and causes - Mayo Clinic
Mar 13, 2019